// https://p5js.org/reference/#/p5/atan2

//'use strict';

​

let targetAngle = 0.0;

let currentAngle = 0.0;

let x = 0.0;

let y = 0.0;

let smoothSpeed = 0.05;

let scl = 25.0;

const count = 3;

let iToTheta;

​

function setup() {

    createCanvas(windowWidth, windowHeight);

}

​

function draw() {

    x = lerp(x, mouseX, smoothSpeed);

    y = lerp(y, mouseY, smoothSpeed);

    targetAngle = atan2(mouseY - y, mouseX - x);

    currentAngle = lerpAngle(currentAngle, targetAngle, smoothSpeed);

​

    background(0);

    push();

    const theta = currentAngle;

    translate(x, y)

    rotate(theta);

    rotate(PI/2);

    rect(0, 0, 20, 40);

    pop();

}

​

// Linear interpolation of an angle.

function lerpAngle(a, b, step) {

    // Prefer shortest distance,

    const delta = b - a;

    if (delta == 0.0) {

        return a;

    } else if (delta < -PI) {

        b += TWO_PI;

    } else if (delta > PI) {

        a += TWO_PI;

    }

    return (1.0 - step) * a + step * b;

}

​